Type bar rebound check mechanisms



June 2, 1959 H. L. LAMBERT 2,839,025

TYPE BAR REBOUND CHECK MECHANISMS Filed Feb. 12. 1958 INVENTOR I HARRY L. LAMBERT United States Patent TYPE BAR REBOUND CHECK MECHANISMS Harry L. Lambert, West Hartford, Conn, assignor to Royal McBee Corporation, Port Chester, N.Y., a corporation of New York Application February 12, 1958, Serial No. 714,894

6 Claims. (Cl. 197-17) This invention relates to devices for reducing type bar rebound; more particularly it relates to mechanisms for checking type bar rebounds having latching means operable in cooperation with type bar driving connections to restrain bouncing of the type bars upon their return to home position after going through a printing stroke.

One of the problems faced by the typewriting industry is how to increase the operating speeds of typewriters employed at the output of automatic data processing equipment to keep pace with the rate at which information may be read out of the mediums employed in data processing systems. The operating speeds of typewriters is limited by the time required for the movement of mechanical parts, the transmission of motion, and the restoration of the parts after each printing action. Rebound of the type bars from the type head rest falls within the last mentioned class of limitations since the time of retraction of the type bars is increased by the rebound time. This rebound is quite appreciable and sufficient time must be provided between successive printing strokes to allow a rebounding type bar to come to rest, thereby to prevent clashing and jamming between a rebounding type bar and the successively actuated type bar. Insofar as is known all the efforts directed at eliminating or reducing type bar rebound have been expended on the development of head rest materials to provide damping. These expedients have been largely unsuccessful and the problem of rebound is still a speed limiting factor.

This invention therefor is directed to means for substantially reducing rebound to the extent that it is no longer a speed limiting factor. In accordance with the invention the type bars are locked against rebound upon returning to rest position after a printing stroke by means of a latch which is effective in cooperation with sub levers in said driving connections, to which type bars are pivotally linked, to prevent rotation of said sub levers due to rebounding type bars immediately after a printing stroke whereby type bar rebound is checked; and to prevent rotation of said sub levers when associated driving connections are inoperative. The construction of said sub levers is such that upon operation of said driving connections an initial translation of said sub levers renders said latch means ineffective to prevent rotation of said sub levers thereby permitting normal operation of the machine.

It is an object of the invention therefor to provide a device for reducing type bar rebound to the extent that it is nolonger a speed limiting factor.

Another object of the invention is the provision of apparatus for reducing the time of retraction of a type bar so as :to permit an increase in typing speed.

A further object of the invention is to provide means for latching type bars upon their return to home position after a printing stroke.

A still further object is the provision of type bar rebound check latch means which does not interfere with Patented June 2, 19.59

r ice 2 the normal operation of the type bars when driven through a printing stroke.

Other objects and many of the attendant. advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

Fig. 1 is a cross sectional view showing the operating mechanisms of an electric typewriter including only those parts necessary to understand the invention and showing an arrangement of the novel parts of the invention in quiescent positions; and

Fig. 2 is a fragmentary view showing the parts in active operative positions.

Referring now to the drawing, wherein like reference numerals represent like or corresponding parts throughout the several views and wherein is shown a preferred embodiment, there is illustrated in Fig. 1 only enough of the well known Royal electric typewriter construction to assist in pointing out the manner in which mechanism embodying the inventionis incorporated in and operative therewith. The typewriter as is understood employs an electrically driven power transmitting element, preferably a snatch roll 11, which operates continuously, and controllable driving connections for operating type bars 12, which connections are normally inoperative or ineffective, but which may be operatively connected to the drive transmitting element through operator controlled levers 13.

The drive connections for each type bar key lever 13 comprises an actuator 17 which extends fore and aft of the typewriter above the snatch roll. All the type bar actuators are connected at their rearwardly extending ends to bell cranks or sub-levers 18 which are slidably and pivotally mounted on a universal rod 19 mounted in a horizontal bar 21 secured to the sides of the typewriter frame.

As is conventional, depression of a key lever 13 rotates associated lever arm 23 clockwise. Clockwise movement of the lever arm 23 causes the rotation of a pawl latching member 24 in a direction as to release a pawl 25, rotatably mounted on the actuator 17, to engage and be driven forwardly by the snatch roll. The forward movement of the pawl carries with it the actuator 17 thereby translating and rotating the bell cranks 18 which cause associated type bars 132 connected thereto by links 27 to go through a printing stroke. As is understood a ribbon vibrator (not shown) is also actuated each printing stroke through a universal bar link 28 connected between the bell crank and a universal bar 29 fulcrumed as at 30. Universal bar link springs 33 secured at one end to the links and at the other end to an anchor plate 34 are adapted, as will hereinafter appear, to return associated bell crank levers to normal positions.

In accordance with the invention each bell crank lever 18 is formed with a step 35on its rearward-1y facing edge. The bell cranks are slidably and pivotally mounted on rod 19 as heretofore stated through the provision of an elongated pivot hole 36. The elongation of the pivot hole is on a line with the dwelling surface of the step 35, which line is substantially perpendicular to the center line 37 of the bell cranks 18. Secured as by bolts 33 to the bar 21 is a bracket 39 formed, as seen in the figures, with a forwardly projecting lip 41 adapted to normally engage the steps 35 thereby to latch the bell crank levers. The normal quiescent position of the parts is as shown in Fig. l; the universal bar link springs 33 biasing the bell crank levers rearwardly so that the forward surfaces of the pivot holes 36 abut the universal rod 19 whereby the lip 41 of the bracket is over the dwelling surface of the steps in the bell cranks. As is obvious the elongation of the pivot holes are related to the depth of the steps.

In operation, upon actuation of a key lever 13, the initial movement of the actuator 17 will cause the bell {crank lever 18 to slide forwardly until the rearward surface of the pivot hole 36 abuts the universal rod 19 as shown in Fig. 2. This initial translatory motion moves the bell crank forwardly and the step out of engagement with the lip 41 thereby unlocking the bell crank lever 18 and allowing it to rotate counterclockwise to effect a normal typing stroke.

On the return stroke the combined action of the universal bar link spring 33 and the momentum of the actuator 17 in its movement back to normal postion will force the bell crank to slide rearwardly and resume its latched position as shown in Fig. 1 at substantially the same time that the type bar 12 reaches its rest position. As is apparent since movement of the type bar toward the platen 43 tends to rotate the bell crank counterclockwise the type bar cannot rebound from the type head rest 42 when its associated bell crank is latched against counterclockwise motion.

It should be understood that the foregoing disclosure relates only to a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.

The invention claimed is:

1. In a typewriting machine having an electrically driven power transmitting element and controllable driving connections for operating type bars, said controllable driving connections comprising bell crank levers adapted when rotated to drive type bars through a printing stroke, means normally latching said bell cranks against rotation, mounting means for said bell cranks for permitting initial translatory motion of said bell cranks upon actuation of said driving connections thereby to unlatch said bell cranks whereby they may rotate, said mounting means permitting translatory motion of said bell brank back to latched position after a printing stroke whereby type bar rebound is checked, and means for returning said bell cranks to latched position.

2. In a typewriting machine having an electrically driven power transmitting element and controllable driving connections for operating type bars, which connections are normally inoperative but which are adapted to be operatively connected to said element through operator controlled key levers, said driving connections comprising a bell crank for each type bar, means for latching said bell cranks when said driving connections are inoperative, means for mounting said bell cranks whereby they are initially translatable from a latched position to a type bar actuating position when said driving connections are operatively connected to said power element, and means for translating said bell cranks back to latched position immediately after completion of a printing stroke whereby type bar rebound is checked. I

3. In a typewriting machine as recited in claim 2 wherein said means for latching said bell cranks in normal inoperative position comprises a step on each of said bell cranks, and stationary means secured on the typewriter for engaging said steps.

4. In a typewriter having a plurality of type bars adapted to be successively driven from a rest position, through a printing stroke and back to rest position, a bell crank associated with each of said type bars, means for operating sai'd bell cranks whereby said type bars are driven through a printing stroke, said bell cranks when operated being adapted to translate and rotate through a printing stroke, means for latching said bell cranks against rotation, said initial translation moving said bell cranks out of latched position, and means for causing said bell cranks to retranslate upon completion of a printing stroke thereby moving said bell cranks into latched position.

5. In a typewriter having a plurality of type bars adapted to be successively powered through a printing stroke, a power transmitting element, linkages selectively engageable with said power transmitting element for powering said type bars, said linkages comprising sublevers translatably and rotatably mounted on a common axis, means for arresting the movement of said linkages at the completion of a printing stroke thereby to prevent rebound of said type bars after completion of a printing stroke, said last named means comprising means for latching said sub-levers against rotation in normal inoperative position, said sub-levers initially translating about their axis when actuated whereby said latching means is rendered ineffective to prevent rotation of said sublevers, and means 'for returning said linkages and sublevers to normal inoperative position at the termination of a printing stroke whereby said latching means is again rendered eifective.

6. In a typewriter having a plurality of pivotally mounted type bars adapted to be successively driven toward a platen and returned to rest position, a continuously driven power element, translatable linkages adapted to be selectively placed into engagement with said element, linkages mounted for translation and rotation about a common axis responsive to translation of said translatable linkages, said type bars being connected to said second named linkages and adapted to be driven through a printing stroke during rotation thereof, latch means for arresting rotation of said second named linkages when said translatable linkages are in an inoperative position, said second named linkages being translatable out of engagement with said latch means 1' in response to the motion of said translatable linkages, and means for returning said second named linkages into engagement with said latch means after completion of a printing stroke.

References Cited in the file of this patent UNITED STATES PATENTS 788,984 Young May 2, 1905 897,269 Brooks Sept. 1, 1908 1,455,112 Crawley May 15, 1923 

